This little-known smartphone has the best battery life I’ve ever tested

Jeff Dunn/Business Insider

Everyone just wants more battery life.

With each passing year, smartphones get thinner, faster, and stronger, with sharper cameras and better displays. But all of that eats power, and lithium-ion batteries are still flawed, needy little things.

There is no perfect way around this. Barring some major technical breakthrough, you simply cannot get a phone that lasts a week off a single charge and adequately performs all the tasks people expect from a modern smartphone.

But the Asus Zenfone 3 Zoom makes the best of what we’ve got today. The latest device from the Taiwanese tech firm is unremarkable from a distance — it’s a midrange Android phone, and there are a million of those. However, by mixing a giant 5,000 mAh battery, an energy-efficient processor, and a good enough display, it lasts longer than any other decently-powerful smartphone I’ve seen.

Whether that’s enough to make it worth your $330, though, is another question. Let’s take a closer look:

The Asus Zenfone 3 Zoom is handsome, but nondescript. It looks a bit like an iPhone. Its edges are rounded, and its back is coated in smooth aluminum. It’s neither thin nor light by modern standards, and it’s too big for most to use comfortably with one hand. It does manage to be lighter and more compact than an iPhone 7 Plus, however, which is impressive considering it has a same-sized screen and a much larger battery.

To be clear, nothing here feels as high-end as a Samsung Galaxy S8 or HTC U11. The aluminum is nice, but the areas above and below the antenna lines are made of a cheaper plastic. It's not waterproof, either, so you'll have to watch for spills. And the bezels around the display are sizable, though that’s understandable with a less expensive device like this.

I’ll also note that I managed to scratch both the back and front of my device without effort. Your mileage may vary here, but in most cases keeping my phone in the same pocket as my keys hasn’t led to those kind of scuffs.

Altogether, though, the design is a plus. Like Lenovo’s Moto G5 Plus, its main competitor, the Zenfone 3 Zoom is affordable without feeling cheap.

The design does cut some corners, though. While the phone uses the newer and faster USB-C standard, it doesn’t support NFC or 5GHz (i.e., faster) WiFi signals. The former is disappointing, but not too surprising for this price range; it mainly means you can’t make contactless payments. The latter is more baffling; it may not be a deal breaker, but those with newer WiFi routers will have to stay on the slower 2.4GHz band.

Also of note: Like many mid-tier unlocked phones, the Zenfone 3 Zoom only works with GSM networks like AT&T and T-Mobile.

Even then, the phone doesn’t support LTE band 12, which helps boost coverage, particularly indoors, with T-Mobile. I could get by without it, but be warned that you may see a downgrade.

By contrast, there are models of the Moto G5 Plus that work with all four of the major US carriers.

It does have a headphone jack, however. What’s more, it’s one of the handful of phones that supports High-Res Audio files. You have to be the kind of audiophile that goes out of their way to download those files in the first place, but in general, audio through the Zenfone 3 Zoom sounds a bit more alive than it might elsewhere.

The speakers on the bottom of the device are decently loud, too. And while we’re talking design, I’ll also note that the fingerprint scanner on the back is nice and fast.